This section is intended to provide a background or context to the invention disclosed below. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise explicitly indicated herein, what is described in this section is not prior art to the description in this application and is not admitted to be prior art by inclusion in this section.
The deployment of Internet of Things (IoT), consisting of devices of various types interconnected for communication, is expected to reach a massive scale in the next few years and wireless connectivity through wide-area networks will be an important component of this future. In 2015, an estimated 0.4 billion IoT devices are connected using cellular networks. This number will grow to 1.5 billion in 2021, equivalent to a yearly growth rate of 27%. In LTE Rel-13 narrowband IoT (NB-IoT) was introduced as a feature to support this expected growth in devices.
NarrowBand IoT (NB-IoT) is a Low Power Wide Area Network (LPWAN) radio technology standard that has been developed to enable a wide range of devices and services to be connected using cellular telecommunications bands. NB-IoT is a narrowband radio technology designed for the Internet of Things (IoT), and is one of a range of Mobile IoT (MIoT) technologies standardized by the 3rd Generation Partnership Project (3GPP).
NB-IoT is designed to have low complexity devices, low-throughput, low-cost, long battery life, and enabling a large number of connected devices. The NB-IoT technology can either be deployed in spectrum allocated to Long Term Evolution (LTE)—“in-band” utilizing resource blocks within a normal LTE carrier, or in the unused resource blocks within a LTE carrier's guard-band—or “standalone” for deployments in dedicated spectrum. It is also suitable for the re-farming of GSM spectrum. Additionally it is designed to have increased coverage capability corresponding to a maximum coupling loss (MCL) of up to 164 dB.
In IoT, a typical traffic profile is for mobile autonomous reporting where a UE will wake up, transmit data, then go back to sleep. Thus, this type of traffic is mostly on the uplink.
FIG. 1 shows the uplink channel structure for NB-IoT which consists of NPUSCH and NPRACH channels. Block 11 represents an NPUSCH of 12 tones as does block 12. Block 13 represents an NPUSCH of 3 tones. Blocks 14 and 15 each represent NPUSCH of 6 tones, while block 16 represents a single-tone NPUSCH.
To address the massive connectivity problem non-orthogonal multiple access (NOMA) on the uplink has been proposed. Traditionally, when users are scheduled in cellular networks, it is done in an orthogonal setting such that users are multiplexed in the time, space, frequency, or code domain in order to minimize interference between users. However, with the explosion in the number of devices desiring access to the network these multiplexing techniques begin to fall short.
NOMA allows users to overload the same resources and then uses multiuser receiver (MUR) techniques in order to decode all the users which share the same resources. There have been many proposals for how to realize NOMA including power domain non-orthogonal multiple access (PD-NOMA), interleave division multiple access (IDMA), and sparse coded multiple access (SCMA).
PD-NOMA takes advantage of users having different received power levels, either through power control or naturally occurring in the network, in order to separate the users. PD-NOMA is used with successive interference cancellation (SIC) in order to cancel higher power signals, which are decoded first, before decoding the other users. SIC allows signals which share either exact same or partial resources to be canceled out from one another if there is a sufficient power difference.
FIG. 2 shows a block diagram of PD-NOMA as an example of an uplink (UL) NOMA system. Block 21 represents the coded bits for user 1 which are resolved by OFDM mapping and modulation in block 23. Likewise, block 22 represents the coded bits for user K which are resolved by OFDM mapping and modulation in block 24. The results of blocks 23 and 24 are passed through the multiple access channel represented by block 25. From there the high-power UE is decoded in block 26 and with successive interference cancellation shown by block 27 sent to a traditional receiver shown by block 28.
The current invention moves beyond these techniques for scheduling overlapping resources for NB-IoT.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
[2] 3GPP: 3rd generation project partner
[3] BLER block error rate
[4] CE coverage enhancement
[5] CRS cell reference signal
[6] DCI: Downlink control information
[7] DL: Downlink
[8] eNB evolved Node B (e.g., an LTE base station)
[9] I/F interface
[10] IoT Internet of Things
[11] LTE long term evolution
[12] MCS Modulation and coding scheme
[13] MTC machine type communication
[14] MME mobility management entity
[15] mMTC massive MTC
[16] NB-IoT Narrow band IoT (internet of things)
[17] NCE network control element
[18] NPDCCH: Narrow band PDCCH
[19] NPDSCH: Narrow band PDSCH
[20] NPRACH: Narrow band PRACH
[21] NRS NB-RS (NB-IoT reference signal)
[22] NRSRP NB-IoT RSRP
[23] N/W network
[24] PRB: Physical resource block
[25] PDCCH: Physical downlink control channel
[26] PDSCH: Physical downlink sharing channel
[27] PRACH physical random access channel
[28] RRC: Radio resource control
[29] RLF radio link failure
[30] RLM radio link monitoring
[31] RRH remote radio head
[32] RSRP Reference Signal Received Power
[33] Rx receiver
[34] SGW serving gateway
[35] SNR signal to noise ratio
[36] Tx transmitter
[37] UE user equipment (e.g., a wireless, typically mobile device)
[38] UL: Uplink